Fit one of the piping bags with a decorative tip. On the remaining bags, cut a 1/4-inch opening to use for the vanilla whipped cream and a 1/2-inch opening for the cocoa whipped cream. Set aside.
For the vanilla whipped cream, combine heavy cream, confectioners’sugar, and vanilla extract in the bowl of a standing electric mixer fitted with the whisk attachment. Mix on low speed to combine and then beat on medium speed until the mixture just holds peaks.
Transfer the mixture to the piping bag with the 1/4-inch opening and place it in the refrigerator (you can rubber band the ends to prevent leakage, but I usually just fold the ends over and let it rest carefully on its side). Reserve the bowl and whisk attachment to use for the cocoa whipped cream.
To prepare the cocoa whipped cream, pour about 1/2 cup of the heavy cream into the mixing bowl. Sift the cocoa and confectioners’ sugar over the top and mix to combine. Add the remaining heavy cream and mix on low speed to begin incorporating the heavy cream. Increase speed to medium and beat until the mixture just holds peaks. Transfer the cocoa cream into the piping bag with the 1/2-inch opening.
Slide the whipped cream-filled piping bags into the remaining piping bag fitted with a decorative tip. Apply even pressure to the top of the pastry bags to merge the vanilla and cocoa whipped cream mixtures together through the piping tip. Pipe as desired.